JPH0628767A - Preserching method - Google Patents

Abstract

PURPOSE:To shorten the time required for presearch. CONSTITUTION:In a presearching method, a magnetic head 6 is reciprocated once between a track N1 and the track N52 in the radial direction of a magnetic disk 3, and presearch is ended. First of all, while moving continuously the magnetic head 6 from a state where the head 6 is placed on the track N1 in the direction of a disk center 4, the presence of records on respective tracks N1-N52 are detected and stored in a memory. Then, when the magnetic head 6 arrives at the track N52, the magnetic head 6 is moved in the reverse direction of the former, and ID data on e. g. a photographing date, etc., is read. At this time, the unrecorded tracks are jumped based on the information on the presence of records on respective tracks detected previously, and the magnetic head 6 is stopped only at the recorded track and the data are read.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a pre-search method applied to a magnetic recording / reproducing apparatus, and more particularly to a pre-search method applied to a still video magnetic disk.

[0002]

2. Description of the Related Art A still video camera photoelectrically converts a subject image by a solid-state image pickup device, captures it as a luminance signal and a color signal, synthesizes these signals by FM modulation, and records them as a multiplexed image signal on a magnetic disk. The method to do is adopted. Further, in still video cameras in recent years, data signals relating to field recording / frame recording discrimination, track numbers, photographing dates, etc. are recorded on a magnetic disk by being superimposed on the image signals by a frequency multiplexing method.

As a modulation method for this data signal, DP is used.
SK (Differential Phase Shift Keying) modulation is used. Therefore, the data signal is DPSK-modulated and stored on the magnetic disk in an overlapping manner with the image signal. Then, at the time of reproduction, a data signal is extracted from the FM modulation signal read from the magnetic disk, the waveform is shaped, and then D
PSK demodulation is being performed.

By the way, on a magnetic disk used in a still video camera, 52 tracks are concentrically formed, and up to 50 tracks from the outer peripheral side of the disk are used for image recording. When recording a new image on a magnetic disk, it is necessary to detect an unrecorded track and specify the track number, and when reproducing a recorded image, the image is recorded. It is necessary to retrieve the track in which is recorded and read the data such as the track number and the shooting date.

In this case, prior to image recording or reproduction, the presence or absence of recording of each track of the loaded magnetic disk and the track number of the recorded track are pre-searched.
This information is stored in memory, and this information is read and used when necessary (pre-search method), and each time an image is recorded or reproduced, the presence or absence of recording of each track and the track number of the recorded track are searched. However, the pre-search method is superior in that the time until recording or reproduction is executed is short.

Conventionally, in this pre-search method, while rotating the magnetic disk, the magnetic head is intermittently moved in the radial direction of the magnetic disk by one pitch of a track from the outer peripheral side of the magnetic disk toward the disk center. However, detection of the presence or absence of recording, reading of data such as the track number when recording has been completed, the date of shooting, etc., and storage of this information in the memory are performed for each track, and the search for the last track is completed. After that, the magnetic head was continuously moved in the opposite direction to the above and returned to the original position.

Since the presence / absence of recording of the track is usually detected based on the envelope detection output obtained by the envelope detection, the detection and determination speed is very fast, but the data such as the track number and the photographing date are recorded. In order to improve the reading accuracy and the like, since the reading is performed a plurality of times, it is necessary to hold the magnetic head on the track for a certain period of time, and since auto-tracking is also performed, it takes some time. In this case, in the above-described conventional pre-search method, the presence or absence of recording of a track and the reading of data are simultaneously performed by scanning the magnetic head in one direction. Therefore, the behavior of the magnetic head in this scanning is such that the search time is long. Should be prioritized. Therefore, it is necessary to perform a search by intermittent movement of temporarily stopping the magnetic head and restarting the movement of all the tracks regardless of whether or not the tracks are recorded, and it takes a long time from the start to the end of the search. There was a drawback of this.

[0008]

SUMMARY OF THE INVENTION An object of the present invention is to provide a pre-search method which can shorten the search time.

[0009]

These objects are achieved by the present invention described in (1) to (4) below.

(1) Information is recorded on each track by moving the magnetic head in the radial direction of the magnetic disk while relatively rotating the magnetic disk in which a plurality of tracks are concentrically arranged and the magnetic head. Is a pre-search method for detecting the presence or absence of recording for reading whether or not the data has been recorded, and for reading information for reading predetermined information recorded on a track. A pre-search method, wherein the presence or absence of recording is detected, the result is stored in a memory, and then the information is read only on a recorded track based on the stored information.

(2) The pre-search method according to (1), wherein the moving direction of the magnetic head at the time of reading the information is opposite to the moving direction of the magnetic head at the time of detecting the presence or absence of the recording.

(3) When performing the information reading, the magnetic head is continuously moved to the above (1) or (2).
Pre-search method described in.

(4) The above-mentioned (1) to (3) for storing track numbers of recorded tracks in the memory.
The pre-search method described in any one of 1.

[0014]

EXAMPLE As described above, the presence or absence of recording of a track is usually detected based on the output obtained by envelope detection, but the detection and determination speed is very high.
Therefore, it is possible to detect and determine even the scanning in which the magnetic head is continuously moved in the radial direction of the magnetic disk, and the scanning can be performed in a short time. Meanwhile, the track number,
Shooting date and shooting time (hereafter simply called shooting date)
It is necessary to make the magnetic head stand still on the track for a certain period of time to read data such as "1". Therefore, it takes some time because the magnetic head is intermittently moved in the radial direction of the magnetic disk.

In the present invention, when the magnetic head is moved back and forth in the radial direction of the magnetic disk, for example, the information on the presence or absence of recording of the track detected in the forward movement is used, and in the backward movement, the non-recorded track is skipped and recorded. Since the data is read only on the tracks that are set, the wasteful time of stopping the magnetic head on the non-recorded track is saved, and the search time is shortened as a whole.

The case where the pre-search method of the present invention is applied to a still video camera will be described in detail below with reference to the accompanying drawings. FIG. 1 is a block diagram showing a configuration example of a still video camera for implementing the pre-search method of the present invention. As shown in the figure, the still video camera 1
Has a system control circuit 10 for controlling various functions of the still video camera described later. The system control circuit 10 is usually composed of a microcomputer.

The still video camera 1 includes a recording / playback unit 2
The recording / reproducing unit 2 is loaded with a magnetic disk 3 as a recording medium for recording an image to be photographed and various data relating to the image, for example, in a state of being housed in a case. The magnetic disk 3 is rotated by a spindle motor 5 at a rotational speed of, for example, about 3600 rpm, and the drive of the spindle motor 5 is controlled by a motor drive circuit 11.

The spindle motor 5 outputs a predetermined number of FG pulses corresponding to the rotation speed of the spindle motor 5. A PG pin and a corresponding PG coil (not shown) are provided near the center 4 of the magnetic disk 3 set on the rotation shaft of the spindle motor 5, so that one PG pulse is generated for each rotation of the magnetic disk. Is output. The system control circuit 10 controls the rotation of the spindle motor 5 based on these pulse signals to rotate the magnetic disk 3 at a constant speed.

Further, the recording / reproducing section 2 has a magnetic head 6
The magnetic head 6 is moved by a stepping motor 7 in the radial direction of the magnetic disk 3. The tracking drive circuit 12 controls the moving amount, moving speed, and moving timing of the magnetic head 6. The tracking drive circuit 12
The operation of the motor drive circuit 11 is controlled by the system control circuit 10.

An operation unit 13 is connected to the system control circuit 10. The operation unit 13 mainly includes the magnetic disk 3
Switch for selecting either recording / reproducing, a recording mode selection switch for selecting one of recording mode, that is, one of field recording / frame recording, and the magnetic head 6 is moved onto a predetermined track of the magnetic disk 3. It has a head feed switch and a release switch (both not shown) for opening and closing the shutter at the time of photographing.

A display unit 14 is connected to the system control circuit 10. In the display unit 14, for example,
Information such as one of the above recording / reproducing, recording mode, track number, recording / unrecording of track, shooting date, presence / absence of loading of the magnetic disk 3, information on power source, information on strobe emission, current time, etc. Information is displayed, for example, by a liquid crystal or a light emitting element. The imaging unit 20 includes a lens system, a diaphragm, a mirror, an optical filter, a shutter, a solid-state imaging device (CCD), and the like (not shown). When the shutter is opened, an image of a subject is formed on the CCD via the lens system and the like. . The CCD may be either a black-and-white image or a color image, but the latter is preferable, which will be described below.

In the CCD section, the formed image is photoelectrically converted to obtain a luminance signal (Y) and a color difference signal (RY, BY).
And output. Of these, the luminance signal is FM-modulated by the luminance signal FM modulation circuit 21. On the other hand, the color difference signal (R
-Y, BY) is line-sequentialized by a line-sequential circuit (not shown) to be a color signal (C), and this color signal (C) is FM-modulated by the color-signal FM modulating circuit 22. Each of the FM modulation circuits 21 and 22 is connected to an adder 23, and the FM-modulated luminance signal and chrominance signal are combined by this adder 23, whereby an image signal corresponding to one still image is generated. .

Further, the adder 23 is connected to the adder 24, and the DPSK modulation circuit 25, the carrier generation circuit 26 and the pulse generation circuit 27 are connected to the adder 24 in this order. The DPSK modulation circuit 25 is a DPS for ID data such as the track number of the magnetic disk 3 and the shooting date.
The K signal is generated, and the carrier (carrier wave) output from the carrier generation circuit 26 is DPSK modulated based on the ID data output from the system control circuit 10. The carrier generation circuit 26 generates carriers based on the pulse signal output from the pulse generation circuit 27.

The pulse signal output from the pulse generation circuit 27 is input to the system control circuit 10, and based on this, the timing of various control operations is adjusted and the DPSK signal is modulated. Further, the pulse signal output from the pulse generation circuit 27 is used for various controls of the CCD in the imaging unit 20. The adder 24 is connected to the recording side terminal 31 of the switch 30 via the amplifier 28. The switch 30 is controlled by the system control circuit 10 so that
When recording images on the magnetic disk 3, the magnetic head 6
And the recording side terminal 31 are connected, and when reproducing an image or the like from the magnetic disk 3, the magnetic head 6 and the reproducing side terminal 32 are switched to be connected.

The reproducing side terminal 32 of the switch 30 is connected to the head amplifier 41, and the head amplifier 41 is further connected.
Are connected to an automatic gain control (AGC) amplifier 42. In addition, the AGC amplifier 42 includes a high-pass filter 4
3, low-pass filter 45 and band-pass filter 4
A luminance signal FM demodulation circuit 44, a color signal FM demodulation circuit 46, and a DPSK demodulation circuit 48 are connected in parallel via 7 respectively.

The luminance signal FM demodulation circuit 44 FM demodulates the luminance signal that has passed through the high-pass filter 43, and preferably has a skew correction function for eliminating distortion on the screen. In addition, the color signal FM demodulation circuit 46
The color signal that has passed through the low-pass filter 45 is FM-demodulated, and preferably, the skew correction function and the line-sequentially recorded color difference signals (RY, BY) are simultaneously output for each horizontal scanning line. It has a synchronization function. The luminance signal FM demodulation circuit 44 and the chrominance signal FM demodulation circuit 46 as described above are respectively connected to the encoder 50 and output as a video signal.

The DPSK demodulation circuit 48 converts the DPSK signal extracted by passing through the bandpass filter 47 into a DPS signal.
The ID data is reproduced by K demodulation, and its output side is connected to the system control circuit 10. In the pre-search described later, the DPSK signal read from the recorded track is processed by the DPSK demodulation circuit 48 into the DPS signal.
This demodulated K data is K demodulated, and the reproduced ID data is reproduced by the system control circuit 1.
0 memory.

A sync signal separation circuit 60 is connected to the output side of the luminance signal FM demodulation circuit 44, and the sync signal separation circuit 60 is connected to the system control circuit 10. The sync signal separation circuit 60 includes a brightness signal, a horizontal sync signal (H-SYNC), and a vertical sync signal (V-SY).
This is a circuit for taking out NC). The horizontal sync signal (H-SY) separated and extracted by the sync signal separation circuit 60.
NC) and the vertical synchronization signal (V-SYNC) are input to the system control circuit 10, respectively, and, for example, I described later.
Used for reading D data, etc.

An envelope detection circuit 70 is connected to the output side of the head amplifier 41, and the envelope detection circuit 70 is connected to the system control circuit 10. This envelope detection circuit 70 is used for the magnetic disk 3
In order to detect the presence or absence of recording on each track and to perform tracking, the envelope detection of the reproduction signal read by the magnetic head 6 is performed. The output obtained by the envelope detection circuit 70 is input to the system control circuit 10 to detect the presence or absence of recording on each track by comparing the output voltage value with a predetermined value, and in the recorded track, The position of the magnetic head 6 is finely adjusted so that the voltage value of the output from the envelope detection circuit 70 becomes maximum, and tracking is performed so that an optimum reproduction signal is obtained.

The procedure for recording an image on the magnetic disk 3 will be described below. First, prior to recording an image, a presearch is performed by the presearch method of the present invention.
This pre-search is executed by the system control circuit 10 according to the flowchart shown in FIG. 2, for example. When the recording / reproducing unit 2 is loaded with the magnetic disk 3, the switch 30 is switched to be connected to the reproducing side terminal 32 to be in a reproducible state, and the spindle motor 5 is driven to rotate the magnetic disk 3. Start (Step 10)
1). The drive of the spindle motor 5 is started automatically, for example, due to the loading of the magnetic disk 3, or manually by the operation unit 13.

Next, the number of rotations of the spindle motor 5 is detected based on the FG pulse and the PG pulse input to the system control circuit 10, and whether or not the rotation of the magnetic disk 3 has reached a steady rotation, that is, rotation lock. It is determined whether or not it is in a state (step 102). When the rotation is locked, the tracking drive circuit 12 drives the stepping motor 7 to move the magnetic head 6 onto the track N1 of the magnetic disk 3 and stop it (step 103).

As shown in FIG. 3, the magnetic disk 3 includes:
A total of 52 tracks are formed concentrically. The track N1 is a track located on the outermost periphery of the magnetic disk 3, and from this, by feeding the magnetic head 6 at the time of recording,
Tracks N2, N3, toward the center of the magnetic disk 3,
N4, N5, N6, N7 ... N48, N49, N5
0, N51 and N52 are formed. Of these,
The tracks N1 to N50 are tracks for image recording, the track N51 is a non-recorded track,
The track N52 is a track on which information other than an image such as a cue signal is recorded.

Next, as shown by the arrow in FIG. 3, the magnetic head 6 is moved in the radial direction of the magnetic disk 3 toward the magnetic disk center 4 (step 104). At this time, it is preferable that the magnetic head 6 moves continuously on each track without being temporarily stopped or decelerated. The moving speed of the magnetic head 6 is not particularly limited, but the moving time of the track pitch (0.1 mm) is preferably 200 msec or less, more preferably 20 for improving the shutter speed.
It is set to be about msec or less.

In moving the magnetic head 6 as described above,
The position of the magnetic head 6 is near the track, that is,
When there is little deviation from the track center and the track has already been recorded, it is judged whether or not the position is such that the output of envelope detection becomes large enough to detect the presence of recording (step 105). It should be noted that this judgment is made based on the feed amount of the magnetic head 6 which is stored in advance in the memory built in the system control circuit 10. When the position of the magnetic head 6 is near the track, it is determined whether or not the track is recorded (steps 106 and 10).
7). This judgment is made based on whether or not the envelope detection output obtained by the envelope detection circuit 70 is a predetermined value or more. It should be noted that envelope detection is generally preferably performed a plurality of times for one track.

As a result of this judgment, when the track (for example, the track N1) is recorded, the fact is written in the DPSK input map formed in the predetermined area of the memory (RAM) of the system control circuit 10 (step). 10
8). Here, each track N is included in the DPSK input map.
For each of 1 to N52, the track number and the fact that the track is recorded can be stored in association with each other.
If there is no recording on the track, DPSK
Next step 10 without writing to the input map
Proceed to 9. Note that instead of such a DPSK input map, a memory that can store the presence or absence of recording for each track number may be used.

Next, it is judged whether or not the track on which the magnetic head 6 is currently located is the track N52 (track number 52) (step 109). If it is not the track N52, the process returns to step 105. Note that such a track number determination can be performed based on, for example, the drive amount (integrated value) of the stepping motor 7 for moving the magnetic head 6. Specifically, the magnetic head 6
Stepping motor 7 to move one track pitch
When, for example, 12 steps are driven, the number of the track on which the magnetic head 6 is located can be known by counting the number of steps.

While the magnetic head 6 continues to move toward the center of the magnetic disk, steps 105 to 109 are repeatedly executed until the magnetic head 6 reaches the track N52. When the magnetic head 6 reaches the track N52, the movement of the magnetic head 6 is temporarily stopped (step 110). Next, it is determined whether or not there is data written in the DPSK input map (step 111). If there is no data (all tracks on the magnetic disk 3 are unrecorded),
The magnetic head 6 is moved onto the track N1 (step 1
17).

When there is even one data written in the DPSK input map, all the data are read and the track numbers are compared with each other to specify the maximum track number. Then, the magnetic head 6 is moved in the opposite direction, that is, toward the outer circumference of the magnetic disk 3 and stopped on the track with the maximum track number (step 112). At this time, the position of the magnetic head 6 is adjusted by automatic tracking (step 113). This automatic tracking is performed by the envelope detection circuit 7
The position of the magnetic head 6 is finely adjusted so that the envelope detection circuit output obtained at 0 becomes maximum.

Next, the tracking movement in step 113 is temporarily stopped (step 114), the DPSK signal relating to the ID data recorded on the track is read, and this reproduced ID data is read by the DP of the system control circuit 10.
Write to SK memory (step 115). This DP
The information written in the SK memory is used when recording or reproducing an image. The reading of the DPSK signal and the writing of the DPSK signal to the DPSK memory are not limited to once but may be performed a plurality of times. In this case, for example, the DPSK signal is continuously detected a predetermined number of times, and the result data is 3
The configuration may be such that when the times are the same, the process moves to the next step.

Next, the DPSK input map is rewritten. That is, the data regarding the track on which the magnetic head 6 is currently located (track number and that there is recording) is erased from the DPSK input map (step 116). After that, steps 111 to 116 are repeatedly executed until there is no data written in the DPSK input map, and when there is no data, the magnetic head 6 is moved onto the track N1 (step 117). After moving the magnetic head 6 onto the track N1, the spindle motor 5 is stopped and the rotation of the magnetic disk 3 is stopped if necessary. Steps 111 to 11 above
At 7, the magnetic head 6 moves intermittently, stopping (or decelerating) at the recorded track. The average moving speed of the magnetic head 6 at this time is influenced by the number of recording tracks, as shown in FIG.

In such a pre-search method, the magnetic head 6 is reciprocated once in the radial direction of the magnetic disk 3 between the track N1 and the track N52 to complete the pre-search. (Movement in the direction of the disk center) is a continuous movement, and therefore the required time is extremely short, and in the backward movement of the magnetic head 6 (movement in the outer circumferential direction of the magnetic disk), the forward movement of the magnetic head 6 detects By using the recorded / non-recorded information of each track, the non-recorded track is skipped, and the magnetic head 6 is stopped only for the recorded track to read the ID data. The wasted time of stopping the head 3 is saved, and the scanning time is shortened as a whole. This effect is particularly remarkable when the number of recorded tracks is small.

In the present invention, the movement of the magnetic head 6 and the presence or absence of recording may be detected before the rotation lock state is established. In this case, when the presence or absence of recording is detected, the decrease in the envelope detection output due to the lower rotation speed of the magnetic disk 3 than in the rotation locked state is taken into consideration. Further, in the illustrated example, the presence / absence of recording is detected for all the tracks. However, the present invention is not limited to this, and the presence / absence of recording is detected only for some tracks, particularly the tracks N1 to N50 for image recording. The configuration may be such that

The presence or absence of recording is detected by the magnetic disk 3
Center N4 side track N52 (or track N50)
You may go from Further, in the illustrated example, the moving direction of the magnetic head at the time of detecting the recording / non-recording of the track is opposite to the moving direction of the magnetic head at the time of reading the ID data, but they may be the same direction.

When the above pre-search is completed, the image of the subject is recorded. In the operation unit 13, for example, field recording is selected by a recording mode selection switch, and the switch 30 is used to switch the recording side terminal 31.
When it is switched to be connected to the system control circuit 10,
The ID data is read from the DPSK memory, the unrecorded tracks are searched, and the track to be recorded is selected from them. This selection is performed by the system control circuit 1
It is preferably done automatically at zero. in this case,
The selection criterion is based on a certain rule, and for example, the unrecorded track having the smallest track number can be selected. Alternatively, the track number of an unrecorded track may be randomly selected.

When the recording track is determined in this way, the magnetic head 6 is moved onto the track. As a result, the recording of the image on the magnetic disk 3 is in a standby state. In the present invention, it is also possible to manually (artificially) select and determine the track to be recorded. For example, the head feed switch of the operation unit 13 is used to sequentially feed the magnetic head 6, and the track to be recorded is selected while confirming whether or not the track displayed on the display unit 14 is recorded.

When the release switch is lightly pressed in the operation section 13, the spindle motor 5 is driven to rotate the magnetic disk 3 and the rotation lock state is reached. When the release switch is further pressed, the shutter is opened in the image pickup unit 20 and the image of the subject is exposed on the CCD. Thus, the luminance signal and the color signal output from the CCD are FM-modulated by the luminance signal FM modulating circuit 21 and the color signal FM modulating circuit 22, respectively, and these are combined by the adder 23 to correspond to one still image. An image signal is generated. Further, the ID data regarding the track number, the shooting date, etc. output from the system control circuit 10 is D
DPSK modulation is performed by the PSK modulation circuit 25, and this DP
The SK signal is combined with the image signal by the adder 24,
These signals are amplified by the amplifier 28 and then recorded on the track via the magnetic head 6.

When frame recording is selected as the recording mode, a combination of two or more unrecorded tracks in a row is searched for, and a combination of tracks to be recorded is determined from among them. If there is no such combination, the recording mode is automatically switched to field recording, and an unrecorded track may be searched. Further, when performing the frame recording, the magnetic head 6 is positioned on one of the two tracks to be recorded, and after the magnetic disk 3 makes one rotation, the magnetic head 6 is moved to the other track. Operate.

Next, a procedure for reproducing an image recorded on the magnetic disk 3 will be described. The reproduction mode is set by a changeover switch (not shown) provided on the operation unit 13. When a new magnetic disk 3 is loaded and the image recorded on the magnetic disk 3 is reproduced, a pre-search similar to the above is performed prior to this reproduction, and each track is recorded in the DPSK memory of the system control circuit 10. ID data such as presence / absence and track number are stored.

After the pre-search is completed, the image is reproduced.
First, the image to be reproduced is selected. Recording of each track from the DPSK memory in order to know which track of the loaded magnetic disk 3 the image is recorded on, and further, for example, information such as the shooting date and recording mode of the recorded image. The ID data such as the presence / absence and the track number is read and displayed on the display unit 14 collectively or for each track. An image to be reproduced can be selected and determined by viewing this display.

Next, the release switch is operated to drive the spindle motor 5 to rotate the magnetic disk 3, and the switch 30 is connected to the reproducing side terminal 32. Note that this step may be performed before the selection of the image to be reproduced. In this state, for example, when the track number of the image to be reproduced is specified by operating the switch on the operation unit 13, the magnetic head 6 moves to the track of that track number and reproduction is performed.

As another method of selecting an image to be reproduced, the head feed switch is operated to move the magnetic head 6, and the track number and the photographing year displayed on the display unit 14 are accompanied with this. You can also select while watching the date. In this case, it is possible to use the ID data relating to the recording / non-recording of the track, which is stored in the DPSK memory, so that the magnetic head 6 moves only to the recorded track each time the head feed switch is pressed. As a result, the time for selecting the image to be reproduced is shortened.

The reproduction signal read by the magnetic head 6 passes through the switch 30 and then the head amplifier 41 and A.
The high-pass filter 43, which is amplified by the GC amplifier 42,
A low-pass filter 45 and a band-pass filter 47 are passed through to extract a luminance signal, a chrominance signal and a DPSK signal in a predetermined wavelength range, respectively. Further, these are a luminance signal FM demodulation circuit 44, a color signal FM demodulation circuit 46 and The signal is supplied to the DPSK demodulation circuit 48, and FM demodulation or D
PSK demodulation is performed. The image signal thus obtained is converted into a video signal and output from the output terminal 51 of the encoder 50 to reproduce the image.

When reproducing an image by frame recording, the magnetic head 6 is positioned on one of the two tracks on which the image is recorded and the magnetic disk 3 is set to 1
After rotating, it operates to move the magnetic head 6 to the other track. The case where the pre-search method of the present invention is applied to the illustrated still video camera has been described above, but the present invention is not limited to this.

Hereinafter, the present invention will be described in more detail with reference to specific examples. (Embodiment 1) Using the still video camera having the circuit configuration shown in FIG. 1, the pre-search method of the present invention was carried out according to the flow chart shown in FIG. As the magnetic disk 3 for the test, images are already recorded on the tracks N1, N2, N3 and N4 (track numbers 1, 2, 3 and 4), and the other tracks N5 to N52 (track numbers 5 to 52) are not recorded. What was a record was used. The moving speed during continuous movement (forward movement) of the magnetic head 6 was set to 8 msec / 0.1 mm (time required to move one track pitch). However, this moving speed is the maximum speed that does not include start, acceleration, deceleration, and stop time. The change over time in the behavior of the magnetic head 6 is shown in FIG.
Is shown in the graph.

(Comparative Example 1) As a conventional pre-search method, the magnetic head 6 of the still video camera is intermittently moved in the radial direction of the magnetic disk 3 by one pitch of a track, and from the track N1 every track. The presence or absence of recording is detected, if recorded, the DPSK signal for the ID data such as the track number and shooting date is read, and the information is written to the DPSK memory, and the last track N52 is searched. After the above, the magnetic head 6 was continuously moved in the opposite direction to the above and returned to the track N1. The moving speed at the time of continuous movement (backward movement) of the magnetic head 6 was the same as in the first embodiment. The change over time in the behavior of the magnetic head 6 is shown in the graph of FIG.

(Example 2) A pre-search was performed in the same manner as in Example 1 except that the moving speed during the continuous movement (forward movement) of the magnetic head 6 was set to 18.0 msec / 0.1 mm. (Comparative Example 2) A pre-search was performed in the same manner as in Comparative Example 1 except that the moving speed at the time of continuous movement (backward movement) of the magnetic head 6 was set to 18.0 msec / 0.1 mm.

(Example 3) A pre-search was performed in the same manner as in Example 1 except that the moving speed of the magnetic head 6 during continuous movement (forward movement) was set to 60.0 msec / 0.1 mm. (Comparative Example 3) A pre-search was performed in the same manner as in Comparative Example 1 except that the moving speed (returning movement) of the magnetic head 6 during continuous movement was set to 60.0 msec / 0.1 mm. The time required for pre-search was measured for each of the above Examples 1 to 3 and Comparative Examples 1 to 3. The results are shown in Table 1 below.
Shown in.

[0058]

[Table 1]

As shown in Table 1, Examples 1 to 3 of the present invention are shown.
It can be seen that in all of the above, the time required for the pre-search is shortened as compared with the corresponding Comparative Examples 1 to 3.

[0060]

As described above, according to the pre-search method of the present invention, the time required for pre-search can be shortened.

[Brief description of drawings]

FIG. 1 is a block diagram showing a configuration example of a still video camera for implementing a pre-search method of the present invention.

FIG. 2 is a flowchart showing an example of a pre-search method of the present invention.

FIG. 3 is a partial plan view showing the configuration of a magnetic disk.

FIG. 4 is a graph showing the change over time in the behavior of the magnetic head in Example 1 of the present invention.

FIG. 5 is a graph showing the change over time in the behavior of the magnetic head in Comparative Example 1.

[Explanation of symbols]

 1 still video camera 2 recording / playback unit 3 magnetic disk 4 center 5 spindle motor 6 magnetic head 7 stepping motor 10 system control circuit 11 motor drive circuit 12 tracking drive circuit 13 operation unit 14 display unit 20 image pickup unit 21 brightness signal FM modulation circuit 22 color signal FM modulation circuit 23, 24 adder 25 DPSK modulation circuit 26 carrier generation circuit 27 pulse generation circuit 28 amplifier 30 switch 31 recording side terminal 32 reproduction side terminal 41 head amplifier 42 AGC amplifier 43 high-pass filter 44 luminance signal FM demodulation circuit 45 low pass filter 46 color signal FM demodulation circuit 47 band pass filter 48 DPSK demodulation circuit 50 encoder 51 output terminal 60 sync signal separation circuit 70 envelope detection circuit 101 to 117 steps

Claims (4)

[Claims] 1. A magnetic disk in which a plurality of tracks are concentrically arranged and a magnetic head are relatively rotated, and the magnetic head is moved in a radial direction of the magnetic disk,
A pre-search method for detecting whether or not information is recorded on each of the tracks and for reading the predetermined information recorded on the track. It is characterized in that the presence or absence of recording is sequentially detected from the side track, the result is stored in a memory, and then the information is read only on the recorded track based on the stored information. Pre-research method. 2. The pre-search method according to claim 1, wherein the moving direction of the magnetic head when reading the information is opposite to the moving direction of the magnetic head when detecting the presence or absence of the recording. 3. The pre-search method according to claim 1, wherein the magnetic head is continuously moved when the information is read. 4. The pre-search method according to claim 1, wherein track numbers of recorded tracks are stored in the memory.